SP542 Thread

[Donovan]

What^ lol.


By the way if you’re using a Cobb tuning system make sure you update your firmware my car is an absolute different animal because I updated my firmware

 

[Gsteve]

Boost

 

[Gsteve]

These spark plugs don't last 100k miles? Why not?

Boost

 

[smurfslayer]

 

[xxaarraa]

Gents, SP578 may have superceded SP542s, but I am reading that they are NOT the same plug and that the 578s are in fact hotter. Ford still offers the cold / 542 plus, under this part number: M-12405-35T. I just ordered two sets from cj pony parts for $95 shipped.

I got this information from this thread:
https://www.f150ecoboost.net/threads/sp578-plugs.77884/page-2

Just wanted to make sure that guys running 542s for a reason just don't blindly switch to 578s thinking they are the same plug. They are not.

 

[Donovan]

Bro...
wtf. I just want cold plugs.

 

[FordPerf Addict]

Anyone getting benefits with these on stock tunes ?


Sent from my iPhone using Tapatalk

 

[New Nick at JDM]

We've ran SP-550's with all our trucks tuned by us so far with zero issues.
We tried NGK 6510's with poor results early on in the tuning process.

The SP-542's are a colder plug than the SP-550 and they seem to have a cult following among raptor owners (obviously lol.)
I cannot comment on the SP-542's personally as we haven't used them in anything other than N/A Coyote CJ's with upwards of 14 to 1 compression with leaded race fuel, but some have stated that they help on stock trucks as well as tuned vehicles.

Gap is also a big factor in plug performance, especially in boosted applications and should be addressed accordingly.
.028" seems to be a sweet spot for these trucks at the boost levels bolt on trucks seem to sustain regardless of plug choice in the end.

 

[Donovan]

^ Agreed. All my issues stopped after I did .028 and used 542s

 

[joey185]

I’m so confused. Is the stock plug a 550?